In the underrated “Faster,” Dwayne Johnson — the wrestler also known as “The Rock” — showed that a rock could cry. He played a morally complex character painted in shades of gray and pulled it off nicely.

In the new “Snitch,” he tries for a similarly layered hero and proves he’s no fluke. But he also proves that every good performer and every good story needs an equally good director. Ric Roman Waugh, a former stuntman on “Lethal Weapon 2,” the original “Total Recall” and “Gone in 60 Seconds,” isn’t quite it.

Ironically, for a stunt person, Waugh’s action scenes in “Snitch” are choppy, and the suspense builds roughly, although the characters do stand out as three-dimensional humans with inner lives.

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In this “inspired by true events” film, Johnson plays John Matthews. The owner of a big construction firm, he is divorced and has a new wife and daughter.

Jason (Rafi Gavron), his son from his previous marriage who unwisely agrees to accept a package “just for a day,” brings down the wrath of the Drug Enforcement Administration and gets arrested, facing at least 10 years in prison.

John learns the sentence could be reduced if Jason cuts a deal and snitches on known drug dealers.

The trouble is, Jason doesn’t know any drug dealers. So John enlists an employee, two-time felon Daniel James (Jon Bernthal), to introduce him to that dark world.

He also agrees to work with a sharp, severe, self-promoting politician (Susan Sarandon) and a grungy, bearded DEA agent (Barry Pepper) to help catch the bad guys.

Eventually, his plan leads him to a big-time drug lord known as “El Topo” (Benjamin Bratt). Of course, it also involves shootouts and chases, all handled with rudimentary displays of style and grace. These scenes — not the social commentary about the brutal unfairness of drug laws — are what make the movie seem long and heavy.

The filmmakers don’t seem to fully understand, or care, about nuances of a civilian becoming involved in complicated drug busts.